A major part of all goods transports in the world today take place by means of containers. Containers are usually handled by different types of lifting devices in the form of industrial trucks and cranes, etc. With the purpose of rationalizing and speeding up the handling of a growing number of containers, there are today lifting yokes intended for, for instance, cranes and that can handle more than one container simultaneously. An example of this is the so-called twin-lift yokes that simultaneously manage to grip and couple two containers that are placed one after the other, i.e., containers that are placed with a respective end portion facing each other, and lift them both in a single lifting step. By lifting two containers simultaneously, valuable handling time is gained and in addition the containers will be exactly placed in relation to each other when putting them down.
If two containers to be lifted happen to stand somehow displaced in relation to each other, which easily may happen, e.g., if they are standing on an uneven substratum and thereby are standing somewhat rotated around the centre axis thereof in relation to each other, or if they are standing at a certain angle in relation to each other, difficulties arise to grip and lock them by the lifting yokes found today. The containers cannot then be lifted directly but the crane operator has to manually direct the different locking devices of the lifting yoke over the corner boxes of the containers where the locking and lifting devices are placed. This requires great concentration from the driver and requires extra time, which lowers the productivity.
Lifting yokes that can lift double containers are per se previously known.
SE527325 discloses, for instance, a container yoke intended to lift two containers placed one after the other, where at least one pair of locking devices or saddles, which are placed at the centre portion of the yoke and intended to grip into and couple/lock in the locking members placed at the short sides of the containers facing each other, are laterally displaceably arranged in relation to the base frame of the container yoke. However, these saddles have to, by the crane operator, be manually steered in over the corner boxes of the containers by means of, for instance, hydraulic control systems, which requires fine maneuvering and great skills of the crane operator and is time-consuming.
Prior art within this area does accordingly not solve the problem of, in a fast, simple and automatic way, reliably gripping, locking and lifting two containers, placed one after the other, that happens to be placed rotated or displaced in relation to each other and then automatically centring the containers during the lifting as well as putting them down in a corrected and optimal way in relation to each other.